A lateral flow assay (LFA) can be a paper-based device that detects a presence of an analyte in a sample. LFAs are a common point of care diagnostic tool. LFAs can function by wicking (e.g., capillary action) a sample of interest through a porous membrane (e.g. paper) where chemical reactions can occur in and on the surface of the porous membrane.
The LFA can contain a conjugate material therein, which are typically formulated to provide a solvent(s) and reactant(s) necessary to dissolve, react, color, tag, or bond to the suspected analyte in a sample. Thus, if the analyte is present, the conjugate or a component thereof will react with the analyte in the sample. The conjugate can include a taggant or other material configured to provide a visual indication of the presence of the analyte, reacted analyte, or analyte-conjugate complex. Typically, the readout of an LFA is a visual change at some point along a length of the LFA. Many LFAs include an analyte collection material near a distal end of the LFA where the analyte and any taggant bonded thereto are bound in large concentration in a sample matrix to provide a visual indication of a positive or a negative result.
Photothermal spectroscopy assay readers can enhance the sensitivity of LFA results beyond visual detection. A photothermal spectroscopy assay reader directs light towards a surface of an LFA that can be saturated with the sample of interest. The conjugate material reacted with the analyte in the sample can absorb energy from the light. The photothermal spectroscopy assay reader can detect a thermal response from the surface of the LFA, which can provide an indication of the presence of the analyte.
Manufacturers and users of photothermal spectroscopy assay readers and LFAs continue to seek photothermal spectroscopy assay readers and LFAs with improved limits of detection.